What Could be wron with my cooker?

A couple of days ago my wife was using a couple of the rings on our ceramic cooker when it blew the main fuse. We switched it on and finished cooking. We have now come to turn the cooker on again and the same thing has happened straight away. When we reset the fuse again and turned it on, it has blown the fuse again and smoke has started coming out of the switch.

We have had an electrician check the house wiring and all is fine. This leads to pointing the finger at the cooker as having a fault.

Does anyone have any ideas as to what it may be?